As you become more experienced in fish-keeping, and more knowledgeable about the needs of your fish, you may want to try your hand at breeding them. Successful breeding in the home aquarium can be immensely rewarding, although it is unlikely to be financially worthwhile! With some species, it is relatively straightforward to encourage them to breed, while others represent a serious challenge; for this reason, many breeders decide to specialize in a particular species so they can develop their expertise.

If you plan to breed fish even on a small scale, you will need to invest in further tanks and equipment, and therefore require extra space. Keen enthusiasts may even establish a devoted ‘fish house’, a specially built unit planned to accommodate their aquaria where young fish may be reared in spacious surroundings.

Colour changes

One of the clearest and most reliable indicators of the onset of breeding condition is a change in the fish’s appearance. Check whether this applies to any of the species you want to breed, so you can be alert for it.

A number of fish become more colourful as they become ready to spawn, particularly the males. Cherry barbs (Barbus titteya), for example, become a much richer shade of red at this stage. Females also swell in size due to their eggs, a change you should notice most clearly when you see the fish from the side.

Triggering spawning

Fish may breed at any time of the year, although you can often encourage them to spawn by making changes in their environment or diet. Success depends in part on replicating the natural triggers, such as a falling water level in the case of annual killifish, or a slight drop in the water temperature, mimicking the effect of an influx of fresh rain water during the wet season which causes rivers and streams to swell. Feeding can also have an impact, with an increased amount of live food often being used to encourage breeding. Some fish may also exhibit changes in their normal behaviour.

Water changes

Spawning triggers differ to some extent from species to species, and not all are equally easy to replicate. A technique worth trying with fish from the Amazon, such as tetras, involves mirroring the natural changes in their water conditions. The water level in the Amazon River and its tributaries may vary considerably through the year. During the dry season, the fish congregate in the remaining areas of water, which contain a greater concentration of pollutants such as decaying vegetation and fish waste.

Once the rains come, the influx of fresh water raises the water level, dilutes the existing water, and lowers the temperature slightly. The increased volume of water, less polluted environment, and resulting proliferation of insect life in the water, triggers reproductive behaviour, with the fish starting to spawn in these conditions within a few weeks.

In an aquarium, you can simply mimic these changes by carrying out a partial water change, raising the water level and reducing the temperature slightly. Adding blackwater extract, which helps to soften the water, is also often recommended for tetras and similar fish in the build-up to spawning activity.

A note of cantion

If your aquarium contains any fish that you have acquired recently, then it is not a good idea to lower the water temperature, because this could be stressful for them. The immune system of fish responds better at higher temperatures, and if they become chilled, they are more vulnerable to opportunistic infections such as fungus. If you have a community aquarium, it may therefore simply be better to transfer the ones you want to breed to a spawning tank, and adjust the heaterstat here for a slightly lower temperature.

Feeding changes

Changing the fish’s food often serves as another potential breeding trigger. It will typically take a fortnight or so for the fish to respond to this change in diet before they show signs of spawning activity.

In the wild, the increase in insect life stimulates many species to come into breeding condition. To mimic this, offer the fish more fresh, invertebrate-based foods, rather than formulated foods.

Beware of using insects or other creatures gathered from the wild, because these can introduce disease to the aquarium. It is better to culture your own supplies of live foods.

There are also special conditioning foods, which are used in conjunction with the fish’s normal diet.

Spawning activity

Even if you have provided a stimulus, you may still be caught unawares by the fish; if they appear more active than usual in the morning, with the male pursuing the female intently, then spawning may well be imminent. If you want to try to control spawning time, you could position the spawning tank so it catches the early morning sun. Take care, especially during the summer, not to site it where it is in full sun for any length of time, however, or the fish will become overheated.

About the Author: Fred Goodson has a passion for pets and animals. He has 4 dogs and is planning to have another one. He is also a blogger who writes about pets and animals. Currently, he is living in New Jersey.